{"id":52,"date":"2026-03-16T18:52:50","date_gmt":"2026-03-16T17:52:50","guid":{"rendered":"http:\/\/www.7virides.com\/cs\/problemy\/dos-skvrny\/"},"modified":"2026-03-25T11:19:47","modified_gmt":"2026-03-25T10:19:47","slug":"dos-skvrny","status":"publish","type":"page","link":"https:\/\/www.7virides.com\/en\/mydlo\/problemy\/dos-skvrny\/","title":{"rendered":"DOS spots: dreaded orange spots and how to prevent them"},"content":{"rendered":"<blockquote>\n<p><strong>TL;DR:<\/strong> DOS (orange spots) = oxidation of unsaturated oils. Risk oils: linseed, hemp, sunflower. Prevention: antioxidants (vitamin E, ROE), quality oils, dark storage. Small DOS are not a health risk, but large ones are not marketable.<\/p>\n<\/blockquote>\n<p>DOS - Dreaded Orange Spots - are orange, brown or yellow spots that begin to appear on the surface or in the cross section of the soap typically 4-8 weeks after manufacture, sometimes sooner. They are one of the most frustrating problems because they affect soap that was seemingly fine at the time of manufacture.<\/p>\n<p>DOS are a flag <strong>Oxidation<\/strong> unsaturated fatty acids - the same process that causes the oil to go rancid. The result is not only an aesthetic blemish, but also an unpleasant rancid smell.<\/p>\n<h2 id=\"co-se-stane-chemie-dos\">What happens: chemistry DOS<\/h2>\n<p>The unsaturated fatty acids (oleic, linoleic, linolenic) in the unsaponified superfat portion of soap are susceptible to oxidation. Oxidation occurs by a chain reaction - one oxidized lipid triggers an adjacent one to spread.<\/p>\n<p>Catalysts of oxidation:<\/p>\n<ul>\n<li>Oxygen from the air<\/li>\n<li>Light (especially UV radiation)<\/li>\n<li>Heat<\/li>\n<li>Presence of metal ions (Cu\u00b2\u207a, Fe\u00b3\u207a) - trace amounts from water or raw materials<\/li>\n<\/ul>\n<p>The presence of antioxidants (vitamin E, ROE) slows down this reaction, not stops it.<\/p>\n<h2 id=\"ktery-olej-zpusobuje-dos-nejcasteji\">Which oil causes DOS most often<\/h2>\n<p>The risk of DOS depends on the degree of unsaturation of the oils in the recipe:<\/p>\n<p><strong>High risk of DOS:<\/strong><\/p>\n<ul>\n<li>Flaxseed oil - highest content of linolenic acid (omega-3), oxidizes very quickly<\/li>\n<li>Hemp oil - high linoleic + linolenic acid<\/li>\n<li>Macadamia oil - palmitoleic acid, relatively unstable<\/li>\n<li>Sunflower (standard) - high linoleic acid<\/li>\n<li>Grapeseed oil - high linoleic acid<\/li>\n<\/ul>\n<p><strong>Medium risk:<\/strong><\/p>\n<ul>\n<li>Olive oil - predominantly oleic (mono) but depends on quality (extra virgin has antioxidants, refined less so)<\/li>\n<li>Almond oil - mono + linoleic<\/li>\n<\/ul>\n<p><strong>Low risk:<\/strong><\/p>\n<ul>\n<li>Coconut oil - saturated fatty acids, very stable<\/li>\n<li>Palm oil - saturated + palmitic<\/li>\n<li>Tallow (tallow) - saturated + oily<\/li>\n<li>Shea butter - oil + stearic<\/li>\n<\/ul>\n<h2 id=\"kdy-dos-prichazi-nejdrive\">When DOS comes first<\/h2>\n<ul>\n<li>Soap with linseed oil: DOS can be visible within 3-4 weeks<\/li>\n<li>Soap with hemp oil: 4-8 weeks<\/li>\n<li>Olive oil soap: 3-12 months (depends on the quality of the oil)<\/li>\n<li>Standard coconut\/palm recipe: 12-24+ months (unless other causes arise)<\/li>\n<\/ul>\n<h2 id=\"proc-dos-prichazi-driv-urychlovaci-faktory\">Why DOS comes early: accelerating factors<\/h2>\n<h3 id=\"zlukle-nebo-stare-oleje\">Rancid or old oils<\/h3>\n<p>Oil that has been poorly stored or is close to its expiry date already contains primary oxidation products (hydroperoxides). These \"inoculate\" the soap - the process is then significantly faster.<\/p>\n<p><strong>Rule:<\/strong> Always sniff the oils before use. Put rancid oil (cardboard, greasy, pungent smelling) in the garbage.<\/p>\n<h3 id=\"kontaminace-kovu\">Metal contamination<\/h3>\n<p>Trace amounts of copper or iron in raw materials or contamination from tools (stainless steel is safe, brass or copper is not) accelerates oxidation.<\/p>\n<p><strong>Rule:<\/strong> Use only stainless steel, plastic or silicon tools and molds.<\/p>\n<h3 id=\"prilis-vysoky-superfat-s-nestabilnimi-oleji\">Too high superfat with unstable oils<\/h3>\n<p>SF 10% from linseed or hemp oil = high proportion of unstable, easily oxidized free fatty acids in soap.<\/p>\n<p><strong>Rule:<\/strong> If using flax or hemp oil, reduce the total SF to 5% or less and add antioxidants.<\/p>\n<h3 id=\"nespravne-skladovani-hotoveho-mydla\">Improper storage of finished soap<\/h3>\n<p>Soap in direct sunlight, in a warm and humid environment (bathroom) or in contact with metal.<\/p>\n<h2 id=\"jak-predchazet-dos\">How to prevent DOS<\/h2>\n<h3 id=\"antioxidanty\">Antioxidants<\/h3>\n<p><strong>Vitamin E (alpha-tocopherol):<\/strong> Add 0.5-1% of the total weight of oils to the trace. Binds free radicals and slows the oxidation chain reaction.<\/p>\n<p><strong>ROE (Rosemary Oleoresin Extract):<\/strong> Stronger than vitamin E. Add 0.1-0.3% of the total weight of oils. Has a stronger herbal scent - almost imperceptible in the finished soap.<\/p>\n<p><strong>Combination:<\/strong> ROE + vitamin E = best protection for formulations with unstable oils.<\/p>\n<h3 id=\"destilovana-voda-misto-kohoutkove\">Distilled water instead of tap water<\/h3>\n<p>Tap water may contain trace amounts of metal ions (Cu, Fe) that catalyze oxidation. Distilled water or filtered water (reverse osmosis) eliminates this factor.<\/p>\n<h3 id=\"omezeni-nestabilnich-oleju\">Restriction of unstable oils<\/h3>\n<ul>\n<li>Flaxseed oil: maximum 5-10% in the recipe, ideally with ROE<\/li>\n<li>Hemp oil: maximum 10-15 %<\/li>\n<li>Sunflower: prefer the high-oleic variant (72% oil instead of 65% linoleic)<\/li>\n<\/ul>\n<p><strong>High-oleic sunflower oil<\/strong> is significantly more stable than standard (conventional) sunflower. It has similar conditioning properties but a much lower linoleic acid content.<\/p>\n<h3 id=\"spravne-skladovani\">Correct storage<\/h3>\n<ul>\n<li>Dark, dry, cool place (cellar, pantry - not bathroom)<\/li>\n<li>Paper or fabric packaging (soap must breathe - it won't last in a fully sealed plastic bag)<\/li>\n<li>Separate from metal surfaces<\/li>\n<\/ul>\n<h2 id=\"co-delat-s-mydlem-ktere-ma-dos\">What to do with soap that has DOS<\/h2>\n<p><strong>Small spots (1-3 dots) in otherwise healthy soap:<\/strong> The soap is safe to use. The orange color and slight rancid smell are aesthetic defects, not a health hazard. Please inform the customer or use for your own use.<\/p>\n<p><strong>Stains spread or the soap smells strongly of rancidity:<\/strong> Soap is not for sale. Stop aging and eliminate from sale.<\/p>\n<p><strong>Entire batch hit by DOS within 4 weeks:<\/strong> Look for the cause - probably rancid oil in the raw material or contamination of the tools.<\/p>\n<h2 id=\"dos-vs-jine-barevne-skvrny\">DOS vs. other colour spots<\/h2>\n<p>Not every orange or brown spot is a DOS:<\/p>\n<p><strong>Vanillin browning:<\/strong> Uniform browning of the entire cross-section, not spots. Vanilla aroma, not rancidity. Causes FO with vanillin.<\/p>\n<p><strong>Stearic spots:<\/strong> White or light grey spots\/grains (not orange). They are caused by unstabilised palm oil or high stearic acid.<\/p>\n<p><strong>Soda ash:<\/strong> White dust coating on the surface (not spots), not in the cross-section.<\/p>\n<p><strong>The natural colour of the oil:<\/strong> Turmeric, spirulina, spinach - color spots when mixed unevenly.<\/p>\n<h2 id=\"rychly-diagnosticky-klic\">Quick diagnostic key<\/h2>\n<table>\n<thead>\n<tr>\n<th>Colour\/appearance of stain<\/th>\n<th>Location<\/th>\n<th>Probable cause<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Orange\/brown, irregular<\/td>\n<td>Surface and cross-section<\/td>\n<td>DOS (oxidation)<\/td>\n<\/tr>\n<tr>\n<td>White, dusty<\/td>\n<td>Just the surface<\/td>\n<td>Soda ash<\/td>\n<\/tr>\n<tr>\n<td>White, granular (dots)<\/td>\n<td>Retrieved from<\/td>\n<td>Stearic spots \/ unsaponified palm<\/td>\n<\/tr>\n<tr>\n<td>Brown darkening of the whole soap<\/td>\n<td>Full cross-section<\/td>\n<td>Vanillin from FO<\/td>\n<\/tr>\n<tr>\n<td>Green \u2192 yellow-brown<\/td>\n<td>Full cross-section<\/td>\n<td>Oxidation of spirulina or matcha<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h2 id=\"caste-otazky\">Frequently asked questions<\/h2>\n<p><strong>Is DOS a health risk?<\/strong> Small VOCs are not a health threat - they are just oxidised fatty acids with an unpleasant smell. They are not suitable for sale.<\/p>\n<p><strong>How long can it take for DOS to appear?<\/strong> Depends on the oil: linseed (3-4 weeks), sunflower (4-8 weeks), olive (3-12 months), coconut (12+ months).<\/p>\n<p><strong>Can an antioxidant prevent DOS altogether?<\/strong> Antioxidants slow down the process, but do not stop it. With risky oils (flaxseed, hemp) the DOS comes later, not never.<\/p>\n<p><strong>Can I combine high superfat with oils at risk of DOS?<\/strong> You shouldn't - a combination of SF 10% + flaxseed oil = DOS in 3-4 weeks. Reduce SF to 5%.<\/p>\n<p><strong>What is the best combination of antioxidants?<\/strong> ROE (0.2%) + vitamin E (0.5%) is very effective. Only vitamin E is cheaper.<\/p>\n<p><strong>How do I store the soap so the DOS doesn't show up?<\/strong> A dark, dry, cool place. Paper wrapper. No metal surfaces. Temperatures below 20 \u00b0C are ideal.<\/p>\n<p><strong>See also:<\/strong><\/p>\n<ul>\n<li><a href=\"\/en\/soap\/soap-making-problems\/soap-troubleshooting-encyclopedia\/\">Troubleshooting encyclopedia<\/a> - overview of all problems<\/li>\n<li><a href=\"\/en\/soap\/soap-making-problems\/soda-ash-soap\/\">Soda ash<\/a> - white surface coating<\/li>\n<li><a href=\"\/en\/soap-making-ingredients\/soap-additives\/\">Soap additives<\/a> - vitamin E and ROE as antioxidants<\/li>\n<li><a href=\"\/en\/soap-making-ingredients\/soap-making-oils-encyclopedia\/\">Oil encyclopedia<\/a> - stability of oils and fatty acids<\/li>\n<\/ul>","protected":false},"excerpt":{"rendered":"<p>TL;DR: DOS (oran\u017eov\u00e9 skvrny) = oxidace nenasycen\u00fdch olej\u016f. Rizikov\u00e9 oleje: ln\u011bn\u00fd, konopn\u00fd, slune\u010dnicov\u00fd. Prevence: antioxidanty (vitam\u00edn E, ROE), kvalitn\u00ed oleje, [&hellip;]<\/p>\n","protected":false},"author":0,"featured_media":0,"parent":18,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"class_list":["post-52","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.7virides.com\/en\/wp-json\/wp\/v2\/pages\/52","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.7virides.com\/en\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.7virides.com\/en\/wp-json\/wp\/v2\/types\/page"}],"replies":[{"embeddable":true,"href":"https:\/\/www.7virides.com\/en\/wp-json\/wp\/v2\/comments?post=52"}],"version-history":[{"count":2,"href":"https:\/\/www.7virides.com\/en\/wp-json\/wp\/v2\/pages\/52\/revisions"}],"predecessor-version":[{"id":193,"href":"https:\/\/www.7virides.com\/en\/wp-json\/wp\/v2\/pages\/52\/revisions\/193"}],"up":[{"embeddable":true,"href":"https:\/\/www.7virides.com\/en\/wp-json\/wp\/v2\/pages\/18"}],"wp:attachment":[{"href":"https:\/\/www.7virides.com\/en\/wp-json\/wp\/v2\/media?parent=52"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}